<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8" />
		<title>Document</title>
	</head>
	<body>
		<script type="text/javascript" >

			let data = function(){
				return {
					a:1,
					b:2,
					c:3
				}
			}

			let s1 = data()
			let s2 = data()
			let s3 = data()

			s1.a = 100

		</script>
	</body>
</html>